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Claude Bazin

Publications and source records attributed to Claude Bazin.

8 recordsLinked to original sources
PubMed2004

Is hobo permissivity related to I reactivity and sensitive to chromatin compaction in Drosophila melanogaster?

In Drosophila melanogaster, the hobo transposable element is responsible for a hybrid dysgenesis syndrome. It appears in the germline of progenies from crosses between females devoid of hobo elements (E) and males bearing active hobo elements (H). In the HE system, permissivity is the ability of females to permit hobo activity in their progeny when they have been crossed with H males. Permissivity displays both intra- and inter-strain variability and decreases with the age of the females. Such characteristics are reminiscent of those for the reactivity in the IR system. The reactivity is the ability of R females (devoid of I factors) to permit activity of the I LINE retrotransposon in the F1 females resulting from crosses with I males (bearing I factors). Here we investigated permissivity properties in the HE system related to reactivity in the IR system. Previously it had been shown that reactivity increases with the number of Su(var)3-9 genes, which increases chromatin compaction near heterochromatin. Using the same lines, we show that permissivity increases with the number of Su(var)3-9 genes. To investigate the impact of chromatin compaction on permissivity we have tested the polymorphism of position-effect variegation (PEV) on the white(mottled4) locus in RE strains. Our results suggest a model of regulation in which permissivity could depend on the chromatin state and on the hobo vestigial sequences.

Animals↗
PubMed2003

Behavior of the hobo transposable element with regard to TPE repeats in transgenic lines of Drosophila melanogaster.

The hobo transposable element of Drosophila melanogaster is known to induce a hybrid dysgenesis syndrome. Moreover it displays a polymorphism of a microsatellite in its coding region: TPE repeats. In European populations, surveys of the distribution of hobo elements with regard to TPE repeats revealed that the 5TPE element is distributed along a frequency gradient, and it is even more frequent than the 3TPE element in Western populations. This suggests that the invasive ability of the hobo elements could be related to the number of TPE repeats they contain. To test this hypothesis we monitored the evolution of 16 lines derived from five initial independent transgenic lines bearing the 3TPE element and/or the 5TPE element. Four lines bearing 5TPE elements and four bearing 3TPE elements were used as a noncompetitive genetic background to compare the evolution of the 5TPE element to that of the 3TPE element. Eight lines bearing both elements provided a competitive genetic context to study potential interactions between these two elements. We studied genetic and molecular aspects of the first 20 generations. At the molecular level, we showed that the 5TPE element is able to spread within the genome at least as efficiently as the 3TPE element. Surprisingly, at the genetic level we found that the 5TPE element is less active than the 3TPE element, and moreover may be able to regulate the activity of the 3TPE element. Our findings suggest that the invasive potential of the 5TPE element could be due not only to its intrinsic transposition capacity but also to a regulatory potential.

Animals↗
PubMed2003

High mutation rate of TPE repeats: a microsatellite in the putative transposase of the hobo element in Drosophila melanogaster.

The hobo transposable element contains a polymorphic microsatellite sequence located in its coding region, the TPE repeats. Previous surveys of natural populations of Drosophila melanogaster have detected at least seven different hobo transposons. These natural populations are geographically structured with regard to TPE polymorphism, and a scenario has been proposed for the invasion process. Natural populations have recently been completely invaded by hobo elements with three TPE repeats. New elements then appeared by mutation, triggering a new stage of invasion by other elements. Since TPE polymorphism appeared over a short period of time, we focused on estimating the mutation rate of these TPE repeats. We used transgenic lines harboring three TPE and/or five TPE hobo elements that had been evolving for at least 16 generations to search for a new TPE repeat polymorphism. We detected three mutants, with four, seven, and eight TPE repeats, respectively. The estimated mutation rate of the TPE repeats is therefore higher than that of neutral microsatellites in D. melanogaster (4.2 x 10-4 versus 6.5 x 10-6). The role of the transposition mechanism and the particular structure of the TPE repeats of the hobo element in this increase in the mutation rate are discussed.

Alleles↗
PubMed2002

Indinavir-induced cholelithiasis in a patient infected with human immunodeficiency virus.

We report the first case of acute cholecystitis due to indinavir-induced cholelithiasis in a patient infected with human immunodeficiency virus who had been receiving indinavir for 56 months. Infrared spectroscopy demonstrated that the gallstone was composed of indinavir monohydrate (50%), calcium bilirubinate (28%), calcium palmitate (10%), cholesterol (7%), and proteins (5%). The role of high-level chronic unconjugated hyperbilirubinemia coupled with high blood concentrations of indinavir is discussed.

Acute Disease↗
PubMed2002

High polymorphism of TPE repeats within natural populations of Drosophila melanogaster: a gradient of the 5TPE hobo element in Western Europe.

To find out whether the polymorphism of TPE repeats of the hobo transposable element observed in some populations results from polymorphism within flies or from variability between flies, or both, we carried out isofemale line analyses of 25 populations. We found that polymorphic populations result from the presence of polymorphic flies combined with interfly variability within these populations. The fact that populations display different levels of polymorphism, i.e., different types of element and different frequencies of polymorphic flies, can be used to differentiate between qualitatively identical populations. This showed that the geographical structuring previously observed is reinforced and, in particular, that the western European populations, which have 3TPE and 5TPE elements, display a centrifugal decrease in the frequency of 5TPE hobo elements which start in western France. This gradient supports the hypothesis of a dynamic invasion by this type of elements: a total invasion by 3TPE elements, followed by further invasions involving other types of hobo elements. Moreover, the analysis of numerous sequences in current populations revealed the existence of seven types of never-previously described hobo elements with regard to TPE repeats. This diversity, which contrasts with the conservation of other parts of the element, highlights the high mutation rate of the S region.

Amino Acid Sequence↗
PubMed2002

Enterococcus gallinarum endocarditis occurring on native heart valves.

We report the first case of Enterococcus gallinarum endocarditis developing on normal native heart valves. Using phenotypic and molecular methods, a precise identification of this naturally vancomycin-resistant species allowed an optimal antibiotic therapy and the patient's recovery.

Aortic Valve↗